POM vs PA (Nylon) — Which Is Better for Your Application?

Quick Summary

If you need dimensional stability, stiffness, and chemical resistance — choose POM. If you need impact strength, wear resistance, and higher temperature tolerance — choose PA.

Mechanical Properties

POM is stiffer and more dimensionally stable. Its flexural modulus is approximately 2800–3500 MPa, compared to PA6’s 1000–3000 MPa (dry). POM’s tensile strength is around 60–70 MPa, while PA6 reaches 70–85 MPa when dry.

In practice, POM maintains its shape better under load and is more predictable for precision applications. PA, on the other hand, offers superior impact resistance and fatigue performance.

Moisture Absorption

This is one of the most significant differences. PA absorbs moisture from the air — PA6 approximately 2.5–3% and PA66 around 2.5%. This changes the material’s dimensions, softens it, and affects mechanical properties significantly.

POM absorbs only 0.2–0.5% moisture, meaning it retains its properties and dimensions virtually unchanged regardless of environmental conditions. This makes POM the superior choice when tight tolerances are required.

Friction and Wear

Both materials perform well in sliding applications, but in different ways. POM has a very low coefficient of friction (approximately 0.2–0.35) and works well in dry conditions without lubrication. PA’s friction is slightly higher when dry but improves significantly in lubricated or wet conditions.

For long-term wear resistance, PA often edges ahead, particularly under heavy loads.

Chemical Resistance

POM resists solvents, fuels, and oils well but cannot withstand strong acids or bases. PA offers better resistance to bases and many chemicals but weakens in acidic environments.

In fuel environments (gasoline, diesel), POM is the clear winner.

Temperature Resistance

PA handles higher temperatures. PA66’s continuous service temperature is approximately 80–120 °C, compared to POM’s 80–100 °C. If your application requires sustained temperatures above 100 °C, PA is the safer choice.

Machinability

POM is one of the best CNC-machinable plastics available. It cuts cleanly, doesn’t string, and isn’t affected by moisture during machining. PA also machines well but can be slightly more stringy and requires consideration of moisture-related dimensional changes.

Typical Applications

Comparison Table

Conclusion

Both materials are excellent engineering plastics, but they serve different needs. POM is the best choice when you need dimensional accuracy, low friction, and chemical resistance — especially for precision-machined components. PA is the stronger choice when your application demands impact strength, wear resistance, and higher temperature tolerance.